Apparatus for the hardening and tempering of workpieces



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H. W. GRONEGRESS APPARATUS FOR THE HARDENING AND TEMPERING 0F WORKPIE(\;ES

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United States Patent Office 3,1865% APPARATUS FOR THE HARDENING AND TEMPERING F WORKPECES Hans Wilheim Griinegress, Gevelsberg, Westphalia, Ger! many, assignor to Firm 7 Paul Ferd. Peddinghaus,

Gevelsberg, Westphalia, Germany Filed Sept. 12, 1962, Ser. No. 223,217 Claims priority, application Germany, Sept. 26, 1961,

Claims. b1. 266-4) In the hardening of steel workpieces by induction or flame heating and quenching the maximum surfacehardness that can be obtained depends on the carbon content of the workpiece. The hardness may be reduced while other properties are improved by the appropriate selection of the quenching medium and conditions. For example, an oil-water emulsion may be used instead of a quenching medium having a rapid action, such as water. In many cases, however, the surface hardness that is obtained in this Way is still very high and the surface of the workpiece is very brittle so that the hardened surface layer may spall off, particularly if the workpieces are subjected to sudden (e.g. impact) stresses. Such quenched workpieces must therefore be tempered or annealed in a subsequent treatment if an appropriate surface quality is to be obtained. Expensive furnace installations have previously been required for this purpose, particularly if the workpieces are long and bulky.

According to the present invention, apparatus for surface hardening metallic workpieces by a quenching and tempering operation comprises a heating device (which, for example, consists of one or more hardening burners, induction coils or the like), a quenching spray spaced from the heating device, an after-cooling spray arranged on the side of the quenching spray remote from the heating device and at an adjustable distance from the quenching spray and means for imparting relative movement between the apparatus and the workpiece to move the workpiece successively past the heating device and the two sprays. The after-cooling spray arranged at an appropriate distance after the quenching spray enables the otherwise necessary separate tempering process to be dispensed with ecause after the incomplete quenching action of the first spray, the core of the workpiece still contains sufiicient heat to ensure that during the further movement of the work-piece in question until it reaches the after-cooling spray this heat travels to the surface of the quenched workpiece and brings the surface to the required tempering temperature. The tempering temperature can be varied over a comparatively wide range by variation of the distance between the two sprays, the distance being relatively short in order to obtain a low tempering temperature while it is made correspondingly larger for higher tempering temperatures. For this purpose the after-cooling spray is advantageously disposed on a slide adjustable in the direction of feed of the workpiece to be hardened.

According to a further feature of the invention, the distance regulation between the two sprays is effected automatically by means of a pyrometer or other temperature radiation measuring instrument which monitors the tempering temperature of the workpiece to be hardened. The measuring beam of the temperature measuring instrument is aimed at a place situated in front of the after-cooling spray, known electrical control and drive means being provided so that the measuring instrument can automatically adjust the slide carrying the after-cooling spray. The adjustment is made in dependence on the workpiece temperature, so that the distance between the two sprays is automatically increased if the required tempering temperature is not obtained, while the distance is reduced if the temperature is exceeded.

It has been found advantageous for the temperature measuring instrument to be movable together with the slide bearing the after-cooling spray, and for the slide to be driven by a motor controlled by the measuring instrument. The combined mobility of the temperatureinstrurnent and the slide bearing the after-cooling spray ensures that the part the'workpiece to be monitored is always at a definite distance in front of the after-cooling spray, so that the control and adjusting movements can be controlled more satisfactorily and simply.

Some examples of'apparatus in accordance with the invention are illustrated diagrammatically in the accom panying drawings inwhioh:

FIGURE 1 is a general arrangement of one form of apparatus; and p FIGURES 2 and 3 show two further forms of the apparatus. l e V As will be shown in FIGUREI, the apparatus comprises a burner 1, a quenching spray 4 situated after the heater in the direction 2 in which a workpiece 3 is fed, and an after-cooling spray 5 which is disposed at a distance a from the spray 4. The burner 1 raises the workpiece 3 to be hardened to the hardening temperature. The a following quenching spray 4 is so operated that the Workpiece passing it at its hardening temperature is-only incompletely quenched. The heat leftin the core of the workpiece passes during the further movement of the For'the above-described hardening and tempering process it is of course unimportant how the required relative movement between the workpiece 3 and the parts 1, 4 and 5 of the hardening apparatus necessary for the process is brought about. In other words, the workpiece 3 may equally well be stationary and the surface-hardening apparatus comprising the burner 1 and the two sprays 4 and 5 be moved over the workpiece. This latter method of operation is preferable, particularly if the workpieces to be hardened are extremely long. The relative movement may also be obtained by simultaneous and appropriately adapted feed movements of both the workpiece 3 and the hardening apparatus.

In the embodiment shown in FIGURE 2, the quenching spray 4 is constructed in the form of an annular spray surrounding the workpiece 3. The after-cooling spray 5 is disposed on a slide 6 which is adjustable'in position in the longitudinal direction of the workpiece 3 within the range 7 shown in chain-dotted lines, A drive 8 is used for this purpose and acts ona driver pin 12 of the slide 6 by way of a pinion 9 and a swivel arm 10 containing a slot 11.

To obtain automatic regulation of the distance a between the two sprays 4 and 5, the, apparatus is also provided with a pyronieter 13. This measuring instrument is preferably rigidly connected to the slide carrying the after-cooling spray 5 so that it participates in its adjustment movements. The measuring beam 14 is aimed at a part 15 of the workpiece 3 situated immediately in front of the after-cooling spray so that the tempering temperature can be measured at that place. The measuring instrument 13 is connected to the drive 8 by control means (not shown but indicated by the line 16) so that the drive automatically adjusts the slide 6 in dependence on the measured workpiece or tempering temperature at the place 15. If the measured temperature is below the re- Patented June 1, 1965 quired tempering temperature, the slide 6 is moved farther away from the quenching spray 4, i.e. the distance a is increased, while conversely if'the required tempering temperature is exceeded the distance a is reduced by appropriate displacement of the slide 6. e

The example shown in FIGURE-3 differs from that shown in FIGURE 2 substantially only in'that in this example adjustment 'of' the slide 6 is obtained not by oscillating drive, but bya motor 17 which acts on' the driver pin'12 of the slide 6 by way of a screw-threaded shaft 18, a nut 19 and an arm 20 rigidly fixed to the nut.

In this case as well the motor 17 can be controlled automatically through a control 16'by the pyrometer 13 moni-. toring the part of the workpiece 3.

For the quenching and tempering process to be performed by meansof the new. surface-hardening apparatus it may be advantageous for the workpiece to be prequenching means rearwardly of saidheating means in said direction for subsequently quenching said surface to a temperature below a predetermined tempering temperature and displaceable relatively to said workpiece in step with said heating means; after-cooling means rearwardly of said quenching means in said direction for cooling said surface upon the temperature thereof exceeding said predetermined tempering temperature upon reheating of said surface by heat retained in said workpiece subsequent to the partial quenching thereof; temperature-responsivedetecting means trained on said surface rearwardly of said quenching means; and mechanism controlled by 'said detecting means forv continuously and automatically adjustheated to about 300 to 600 C. in: order to assist the performed by the heat stored in the workpiece. Such pre-heating can be produced by conventional means, for example by pre-heating burners or else, in a suitably constructed furnace; V 7 As already stated, when very long workpieces have to be surface-hardened, it is advisable for them to be stationary and for. the burner 1 together with the, sprays 4 and 5, the temperature measuring instrument 13 andthe driving or adjusting means for the slide'6 to:perform the feed movement. In this case the parts of the hardening apparatus. are advantageously disposed on a common frame which is moved along the workpiece axis, the slide 6 which bears the after-cooling spray 5 being mounted so that it-is adjustable in position on the frame in order to adjust the distance a.

I claim: t 1. An apparatus for the surface-hardening and tempering of a metallic workpiece, comprising heating means displaceable relatively to said workpiece for substantially uninterruptedly and progressively heating said workpiece to a temperature sufiicient to harden a surface thereof upon relative displacement of said workpiece and said heating means in a predetermined direction; partial tempering effect required between the'two sprays 4 and 5 ing the distancebetween said after-cooling means and said quenching means.

2. An apparatus as'defined in claim 1 wherein said detecting means is trained on said surface just forwardly of said after-cooling means and is displaceable relatively to be workpiece together therewith. e

3. An apparatus as defined in claim}, further com"- prising a slide shiftable along said surface of said workpiece and carrying said after-cooling means and said detectingmeans, said mechanism including reversible motor means for adjustably controlledly shifting said slidein response. to the temperature sensed by said detecting means.

4. An apparatus as defined in claim 3 wherein .said

, reversible motor means is provided with a'lead'screw operativelyconnected with said slide.

References Cited by the Examiner UNITED STATES PATENTS 2,215,576' .9/40 Bucknam et al 266-4 2,382,515 8/45 Smith.

JOHN F. CAMPBELL, Primary Examiner.

JAMES H. TAYMAN, 111., MORRIS O. WOLK,

Examiners. 

1. AN APPARATUS FOR THE SURFACE-HARDENING AND TEMPERING OF A METALLIC WORKPIECE, COMPRISING HEATING MEANS DISPLACEABLE RELATIVELY TO SAID WORKPIECE FOR SUBSTANTIALLY UNINTERRUPTEDLY AND PROGRESSIVELY HEATING SAID WORKPIECE TO A TEMPERATURE SUFFICIENT TO HARDEN A SURFACE THEREOF UPON RELATIVE DISPLACEMENT OF SAID WORKPIECE AND SAID HEATING MEANS IN A PREDETERMINED DIRECTION; PARTIAL QUENCHING MEANS REARWARDLY OF SAID HEATING MEANS IN SAID DIRECTION FOR SUBSEQUENTLY QUENCHING SAID SURFACE TO A TEMPERATURE BELOW A PREDETERMINED TEMPERING TEMPERATURE AND DISPLACEABLE RELATIVELY TO SAID WORKPIECE IN STEP WITH SAID HEATING MEANS; AFTER-COOLING MEANS REARWARDLY OF SAID QUENCHING MEANS IN SAID DIRECTION FOR COOLING SAID SURFACE UPON THE TEMPERATURE THEREOF EXCEEDING SAID PREDETERMINING TEMPERING TEMPERATURE UPON REHEATING OF SAID SURFACE BY HEAT RETAINED IN SAID WORKPIECE SUBSEQUENCE TO THE PARTIAL QUENCHING THEREOF; TEMPERATURE-RESPONSIVE DETECTING MEANS TRAINED ON SAID SURFACE REARWARDLY OF SAID QUENCHING MEANS; AND MECHANISM CONTROLLED BY SAID DETECTING MEANS FOR CONTINUOUSLY AND AUTOMATICALLY ADJUSTING THE DISTANCE BETWEEN SAID AFTER-COOLING MEANS AND SAID QUENCHING MEANS. 